The use of communication systems through which to communicate data in separate locations is a pervasive adjunct of modem society. Many different types of communication systems have been developed and implemented to be used to effectuate the communication of data between two or more locations.
New types of communication systems have been proposed, developed, and implemented that make use of advancements in communication technologies. Radio communication systems are exemplary of communication systems which have benefited from the advancements in communication technologies. New types of radio communication systems have been proposed, developed, and implemented that take advantage of such advancements in communication technologies. Improvements to existing types of radio communication systems have also been made possible as a result of the advancements in communication technologies.
Increased communication mobility is inherent in a radio communication system. Unlike a conventional, wireline communication system, a wireline connection is not required to be maintained between endpoints, i.e., sending and receiving stations, of the communication system. Radio links, instead, are used upon which to define communication channels upon which to communicate data between the endpoints.
The advancements in communication technologies, include, for instance, advancements in digital communication techniques. The use of digital communication techniques permits the communication capacity of a communication system to be increased, as well as also to improve the quality levels of communications effectuated in the communication system.
Data that is to be communicated in a digital communication system is digitized. Once digitized, the digitized data is formatted, such as into data packets or frames, and converted into a form to permit its communication upon the communication channel. In an ideal communication system, the data packets, subsequent to transmission upon the communication channel and received at a receiving station, are substantially identical in value to the corresponding data packets prior to their communication upon the communication channel. In an actual communication system, however, distortion is introduced upon the data during its communication upon the communication channel such that the values of the data, when received at a receiving station, differ, in part, with corresponding values of the data packets prior to their communication upon the communication channel. If the amount of distortion is significant, the informational content of the data cannot be recovered at the receiving station.
Multi-path transmission, for instance, causes fading of the data. Such fading might alter the values of the symbols of a data packet during its transmission upon the communication channel. If the alteration in the values is not properly corrected, resultant communication quality levels of the communications are, at a minimum, reduced.
Fading of the data upon the communication channel is not necessarily, and, quite likely, is not, constant. That is to say, the fading conditions vary as a function of time. During a single communication session, for instance, the fading conditions upon the communication channel might differ significantly.
Various techniques are utilized to ensure better that the data originated at a sending station is received at a receiving station of signal quality levels that permit the informational content of the data to be recreated. The complexity of the modulation by which the data is modulated at a sending station, prior to its communication upon the communication channel to the receiving station, is selected pursuant to the fading conditions upon the communication channel. If significant levels of fading are exhibited upon the communication channel, a reduced-complexity modulation technique is used to modulate the data. And, when the communication channel exhibits relatively low amounts of fading, an increased-complexity modulation techniques can, instead, be utilized. Adaptive modulation schemes have been proposed by which to adaptively select the modulation complexities by which to modulate the data, responsive to channel conditions of the communication channel. Other operational parameters of communication systems have analogously also been proposed.
Selection of the operational parameters, such as the modulation complexity level, by which data is communicated, is sometimes problematic.
Utilization of conventional information-theory techniques by which to select the operational parameters are sometimes unable to be utilized in a radio communication system. When deterministic analytical techniques are utilized, only basic scenarios are able to be adequately modeled. Fast multi-path fading conditions on the communication channel might well be beyond the capability of control utilizing the deterministic analytical techniques. Heuristic approaches are sometimes unable to be used to select operational parameters in an optimal manner. Existing control schemes are, therefore, sometimes inadequate to select the operational parameters.
An improved manner by which to select the operational parameters, such as the adaptive modulation switching thresholds used in an adaptive modulation scheme, is, therefore, required.
It is in light of this background information related to the selection of operational parameters in a radio communication system that the significant improvements of the present invention have evolved.